Heat oven to 350°.,In ungreased 9 x 13-inch cake pan, stir together flour, sugar, 1/4 cup cocoa, salt and baking powder.,Mix milk, oil and vanilla into flour mixture.,Stir with fork until smooth.,______,Sprinkle 1/4 cup cocoa and brown sugar over batter.,Pour the hot tap water over batter. Bake 40 minutes.,Let stand 15 minutes.,Spoon in dishes, top with ice cream and spoon sauce over each serving or serve alone.